Elevator employee Dennis Black loads corn into a trailer for area farmers at the North Iowa Cooperative on Monday, Oct. 7, 2013, in Thornton, Iowa. / Charlie Neibergall, AP

by Emily Schettler, The Des Moines Register

by Emily Schettler, The Des Moines Register

DES MOINES, Iowa -- Six Chinese nationals have been indicted as part of an ongoing agriculture espionage case involving the attempted theft of valuable trade secrets from three U.S.-based seed manufacturing companies, federal prosecutors announced Thursday.

The indictments came about one week after one of the men, Mo Hailong, was arrested for allegedly conspiring to steal inbred corn seed and transport it to China for use at a China-based seed company.

The seeds represent several years of research worth at least $30 million to $40 million, federal prosecutors said.

Mo became a lawful permanent resident of the U.S. in 2005 and lives in Miami. Four other defendants are residents of China who were visiting the U.S. on combination business and tourism visas when the attempted thefts reportedly occurred. The sixth suspect is a citizen of Canada and China, and was living in Quebec at the time.

Mo had an initial court appearance on Dec. 11 in Miami. The other defendants - Li Shaoming, Wang Lei, Wang Hongwei, Ye Jian and Lin Young - have not appeared in court, said Kevin VanderSchel, first assistant U.S. Attorney for the Southern District of Iowa. He declined to say where the suspects were or whether officials will seek extradition to return them to the U.S. if they are no longer in the country.

The U.S. has an extradition treaty with Canada but not with China, VanderSchel said. All of the suspects face up to 10 years in prison and fines of $5 million.

Mo's attorney, Valentin Rodriguez Jr., did not return a request for comment Thursday.

Court documents indicate that at least five of the suspects are employed by the Beijing Dabeinong Technology Group Co. or its corn seed subsidiary Beijing Kings Nower Seed.

The attempted theft reportedly occurred between September 2011 and October 2012, when prosecutors say the men took inbred seedlings and mature corn ears from fields across Iowa and Illinois belonging to DuPont Pioneer, Monsanto and LG Seeds.

They also illegally obtained packages of hybrid corn and made attempts to smuggle the material out of the country, court documents say.

VanderSchel declined to comment on whether any corn was successfully removed from the U.S.

Inbred seeds are valuable because they pass on drought- and pest-resistant traits to planting seeds that can be grown and harvested.

Mo also used an alias to tour DuPont Pioneer's headquarters in Johnston, Iowa, and Monsanto's research facility in Ankeny and to attend a state dinner hosted by Gov. Terry Branstad to welcome Xi Jinping, the then-future president of China, court documents allege.

Branstad told reporters Monday that the apparent theft could affect the state's relationship with China, which the governor has sought for decades to forge.

"I believe it may present some additional challenges in terms of our relationship between the two countries, but this is a particular incident," Branstad said.

VanderSchel said Thursday the Iowa case is independent from other agriculture espionage cases around the country, including one in Kansas that was also made public last week. That case involved the alleged theft of genetically engineered rice.